﻿#pragma once
#include <iostream>
#include <vector>
#include <time.h>
#include <assert.h>
#include <thread>
#include <mutex>
#include <atomic>
#include <unordered_map>

#ifdef _WIN32
	#include <windows.h>
#else
	// ...
#endif

using std::cout;
using std::endl;


#ifdef _WIN64
	typedef unsigned long long PAGE_ID;
#elif _WIN32
	typedef size_t PAGE_ID;
#else
	// linux
#endif

static const size_t MAX_BYTES = 256 * 1024;
static const size_t NUM_FREELIST = 208;
static const size_t NPAGES = 129;
static const size_t PAGE_SHIFT = 13;


// 直接去堆上按页申请空间
inline static void* SystemAlloc(size_t kpage)
{
#ifdef _WIN32
	void* ptr = VirtualAlloc(0, kpage << 13, MEM_COMMIT | MEM_RESERVE, PAGE_READWRITE);
#else
	// linux下brk mmap等
#endif

	if (ptr == nullptr)
		throw std::bad_alloc();

	return ptr;
}

inline static void SystemFree(void* ptr)
{
#ifdef _WIN32
	VirtualFree(ptr, 0, MEM_RELEASE);
#else
	// sbrk unmmap等
#endif
}


static void*& NextObj(void* obj)
{
	return *(void**)obj;
}
//管理切分好的小块内存对象的自由链表
class FreeList
{
public:
	//头插
	void Push(void* obj)
	{
		assert(obj);
		NextObj(obj) = _freeList;
		_freeList = obj;
		_size++;
	}
	void PushRange(void* start, void* end,size_t n)
	{  
		NextObj(end) = _freeList;
		_freeList = start;
		_size += n;
	}
	//头删
	void* Pop()
	{
		assert(_freeList);
		void* obj = _freeList;
		_freeList = NextObj(obj);
		_size--;
		return obj;
	}
	void PopRange(void*& start, void*& end, size_t n)
	{
		assert(n <= _size);
		start = _freeList;
		end = start;
		for (size_t i = 0; i < n - 1; i++)
		{
			end = NextObj(end);
		}
		_freeList = NextObj(end);
		NextObj(end) = nullptr;
		_size -= n;
	}
	bool Empty()
	{
		return _freeList == nullptr;
	}
	size_t& MaxSize()
	{
		return _maxSize;
	}
	size_t Size()
	{
		return _size;
	}
private:
	void* _freeList = nullptr;
	size_t _maxSize = 1;
	size_t _size = 0;
};



// 管理对⻬和映射等关系
class SizeClass
{
public:
	// 整体控制在最多10%左右的内碎⽚浪费
	// 根据对象大小按一定规则进行对齐
	// [1,128]                  8byte对⻬       freelist[0,16)
	// [128+1,1024]             16byte对⻬      freelist[16,72)
	// [1024+1,8*1024]          128byte对⻬     freelist[72,128)
	// [8*1024+1,64*1024]       1024byte对⻬    freelist[128,184)
	// [64*1024+1,256*1024]     8*1024byte对⻬  freelist[184,208)

	//_RoundUp是RoundUp的子函数，辅助RoundUp函数
	//自我实现版
	/*size_t _RoundUp(size_t size, size_t alignNum)
	{
		size_t alignSize = 0;
		if (size % alignNum != 0)
		{
			alignSize = (size / alignNum + 1) * alignNum;
		}
		else
		{
			alignSize = alignNum;
		}
		return alignSize;
	}*/

	//高手实现_RoundUp方法
	//位运算效率高
	static inline size_t _RoundUp(size_t bytes, size_t align)
	{
		return (((bytes)+align - 1) & ~(align - 1));
	}
	//返回对齐后的大小
	static inline size_t RoundUp(size_t size)
	{
		if (size <= 128)
		{
			return _RoundUp(size, 8);
		}
		else if (size <= 1024)
		{
			return _RoundUp(size, 16);

		}
		else if (size <= 8 * 1024)
		{
			return _RoundUp(size, 128);
		}
		else if (64 * 1024)
		{
			return _RoundUp(size, 1024);
		}
		else if (256 * 1024)
		{
			return _RoundUp(size, 8 * 1024);
		}
		else
		{
			return _RoundUp(size, 1 << PAGE_SHIFT);
		}
	}
	//_Index是RoundUp的子函数，辅助Index函数
	//自我实现版
	/*static inline size_t _Index(size_t size, size_t alignNum)
	{
		if (size % alignNum == 0)
		{
			return size / alignNum - 1;
		}
		else
		{
			return size / alignNum;
		}
	}*/
	//高手实现版
	//位运算效率高
	static inline size_t _Index(size_t size, size_t align_shift)
	{
		return ((size + (1 << align_shift) - 1) >> align_shift) - 1;
	}
	// 计算映射的哪⼀个⾃由链表桶
	static inline size_t Index(size_t size)
	{
		assert(size <= MAX_BYTES);
		// 每个区间有多少个链
		static int group_array[4] = { 16, 56, 56, 56 };
		if (size <= 128)
		{
			return _Index(size, 3);
		}
		else if (size <= 1024)
		{
			return _Index(size - 128, 4) + group_array[0];
		}
		else if (size <= 81024)
		{
			return _Index(size - 1024, 7) + group_array[1] + group_array[0];
		}
		else if (size <= 64 * 1024)
		{
			return _Index(size - 8 * 1024, 10) + group_array[2] +
				group_array[1] + group_array[0];
		}
		else if (size <= 256 * 1024)
		{
			return _Index(size - 64 * 1024, 13) + group_array[3] +
				group_array[2] + group_array[1] + group_array[0];
		}
		else 
		{
			assert(false);
		}
		return -1;
	}
	// ⼀次thread cache从中⼼缓存获取多少个
	static size_t NumMoveSize(size_t size)
	{
		assert(size > 0);
		// [2, 512]，⼀次批量移动多少个对象的(慢启动)上限值
		// ⼩对象⼀次批量上限⾼
		// ⼩对象⼀次批量上限低
		int num = MAX_BYTES / size;
		if (num < 2)
			num = 2;
		if (num > 512)
			num = 512;
		return num;
	}

	// 计算⼀次向系统获取⼏个⻚
	// 单个对象 8byte
	// ...
	// 单个对象 256KB
	static size_t NumMovePage(size_t size)
	{
		size_t num = NumMoveSize(size);
		size_t npage = num * size;
		npage >>= PAGE_SHIFT;
		if (npage == 0)
			 npage = 1;
		return npage;
	}

};

//管理多个连续页大块内存的跨度结构
struct Span
{
	PAGE_ID _pageId = 0; //大块内存页的起始页号
	size_t _n = 0; //页的数量

	Span* _next = nullptr;; //双向链表结构
	Span* _prev = nullptr; //
	size_t _useCount = 0; //切好的小块内存被分给threadcache 的计数
	void* _freeList = nullptr; //切好的小块内存的自由链表
	bool _isUse = false; //该Span是否被使用
	size_t _objSize = 0; //切好的小块内存的大小
};



class SpanList
{
public:
	SpanList()
	{
		_head = new Span;
		_head->_next = _head;
		_head->_prev = _head;
	}
	bool Empty()
	{
		return _head->_next == _head;
	}
	Span* Begin()
	{
		return _head->_next;
	}
	Span* End()
	{
		return _head;
	}
	void Insert(Span* pos, Span* newSpan)
	{
		assert(pos);
		assert(newSpan);
		Span* prev = pos->_prev;
		Span* next = prev->_next;
		// prev newSpan pos
		prev->_next = newSpan;
		newSpan->_prev = prev;
		pos->_prev = newSpan;
		newSpan->_next = pos;
	}
	void PushFront(Span * span)
	{
		Insert(Begin(), span);
	}
	Span* PopFront()
	{
		Span* front = Begin();
		Erase(front);
		return front;
	}
	void Erase(Span * pos)
	{
		assert(pos);
		assert(pos != _head);
		Span* prev = pos->_prev;
		Span* next = pos->_next;
		prev->_next = next;
		next->_prev = prev;
	}
	/*std::mutex& GetMutex()
	{
		return _mutex;
	}*/
private:
	Span* _head;
public:
	std::mutex _mutex;//桶锁
};

